1. Field of the Invention
The present invention relates to a disk apparatus for positioning a head in an arbitrary track on the disk recording surface. More particularly, the invention relates to a disk apparatus having a latch mechanism for retracting and holding the head at a latch position during inactivation.
2. Description of the Related Art
In a rotary type actuator of a magnetic disk apparatus, it is the conventional practice to rotatably attach an actuator assembly which supports the head at the leading end and having a coil at a rear end thereof to an enclosure base by a shaft, arrange the actuator assembly coil relative to a magnetic circuit unit composed of a magnet secured to the enclosure base and a yoke to form a voice coil motor, and recording or reproducing data by positioning the head at an arbitrary track on the disk recording surface by means of driving by the voice coil motor.
Such a rotary type actuator of a magnetic disk apparatus has a latch mechanism which retracts and holds the head into a ramp load mechanism arranged, for example, on the outer periphery of the disk in an inactive state in which the unit is in stoppage.
Known conventional latch mechanisms in a rotary type actuator include:
(1) Magnet latch mechanism, and
(2) Mechanical latch mechanism.
FIG. 1 illustrates an example of the conventional magnet latch mechanism, in which a rotary type actuator 100 has an arm 104 provided in front of a shaft 102, and a head 122 is supported at the leading end of the arm 104 via a suspension 120. Behind the shaft 102 of the rotary type actuator 100, a coil arm 106 is formed to which a coil 108 is attached.
A magnetic circuit unit composed of a yoke and a magnet is secured to an enclosure base 101 facing a coil 108 of the rotary type actuator 100. In FIG. 1, an upper yoke is omitted, showing a magnet 110 positioned below the coil 108 and a lower yoke 111.
A magnet latch 124 having rubber 132 wound around the magnet is arranged in the enclosure base 101 behind the rotary type actuator 100. In the state shown, the rotary type actuator 100 is at a latch position where the head 122 at the leading end is rotated in a ramp load mechanism 126. At this point in time, a magnet 128 attached to the leading end of a latch arm 112 extending from the coil arm 106 behind the rotary type actuator 100 attracts a magnet latch 124 via the rubber 132, and holds it at the latch position.
FIG. 2 illustrates an example of the conventional mechanical latch mechanism. A latch arm 134 is arranged in the enclosure base 101 behind the rotary type actuator. The latch arm 134 is an arcuate member rotatably supported by a shaft 136 has steel balls 138 and 140 attached to both ends. A lever 142 projects on the steel ball 138 side, and an operating lever 144 projects from the coil arm 106 toward the lever 142.
When this mechanical latch mechanism drives the rotary type actuator 100 clockwise and retracts the head 122 into the ramp load mechanism 126, the operating lever 142 projecting from the coil arm 106 pushes the lever 144. As a result, the latch arm 134 revolves anticlockwise, presses the steel ball 140 against the magnet 110 and holds it at the latch position.
Various other latch mechanisms are available apart from the above, and latch mechanism in general can be broadly classified into magnet latch mechanisms and mechanical latch mechanisms.
However, such latch mechanisms of the conventional rotary type actuator suffer from the following problems.
In the magnet latch mechanism shown in FIG. 1, in which the magnet latch 124 is arranged far from the actuator rotation center, increased inertial moment leads to a lower head speed upon seek operation.
The rotary type actuator 100 is pressed strongly against the rubber 132 of the magnet latch by attraction force of the magnet latch. When the coil arm 106 attracts the rubber 132 of the magnet latch 124, causing separation from the latch position and start of seek operation, therefore, an attraction trouble may be caused in which it is not separated from the magnet latch 124.
It is necessary to arrange a latching magnet 128 comprising another member, resulting in an increase in the number of parts and a design limitation. Furthermore, contact between the rubber 132 wound on the magnet latch 124 and the rotary type actuator 100 side may cause contamination by peeled pieces generated by the contact adhering to the disk.
In the mechanical latch mechanism shown in FIG. 2, as in the magnet latch mechanism, the increase in the inertial moment is a problem, and in addition, it is necessary to arrange component parts for latching. This leads to problems of an increased number of parts, and hence to an increase in the number of assembling processes, and of a large design limitation in space.